Men diagnosed with advanced prostate cancer have a median survival of about 30 months, with many patients surviving as along as 5 to 10 years. This relatively slow progression of advanced disease distinguishes prostate cancer from other common malignancies and creates a situation in which men age in the context of premature and severe male hormone deprivation due to adjuvant therapies. This hormone deprivation may well hasten mental and physical deterioration and lower the quality of life in a number of spheres. Since testosterone can be converted to estrogen, certain physical and mental effects of testosterone could reflect its peripheral conversion (via aromatase) to estradiol. Conversely, some of the negative effects of testosterone deprivation by LHRH agonists or therapeutic castration could be due to lowered levels of estradiol. Moreover, clinical and animal studies suggest psychosocial and physical health benefits from estrogen in males. It's reduction in prostate cancer patients, therefore, could contribute to their morbidity. We propose a prospective, blinded clinical trial of low-dose estradiol to test our major hypothesis that chronic, low dose oral 17-beta estradiol therapy will preserve the overall quality of life and mental, emotional, and physical health status of men maintained on treatment-related androgen deprivation. We will enroll 150 cognitively intact (Mini-Mental Status Exam score >23) metastatic prostate patients into a double-blind, placebo controlled prospective study of low-dose estrogen (17-beta micronized estradiol 0.5 mg per day) for one year. We will measure various aspects of quality of life and physical, mental, and social functioning at 10 weeks (T2), 6 months (T3) and 12 months (T4) after study entry.